#!/usr/bin/env node
const { Readable } = require('stream');
//--
//const Read = require('stream').Readbale;
const rs = new Readable();
let c = 'a'.charCodeAt(0);

rs._read = () => {
  rs.push(String.fromCharCode(c++));
  if(c === 'z'.charCodeAt(0) + 1) rs.push(null);
}
//拉取
rs.pipe(process.stdout);
